White light is in one case dispersed by refraction on passing through a glass prism and in a second case diffracted by means of a grating.When the red component and the blue component are considered,it is found that
A)red is both refracted and diffracted at greater angles than blue.
B)blue is both refracted and diffracted at greater angles than red.
C)red is refracted at a greater angle than blue,but blue is diffracted at a greater angle than red.
D)blue is refracted at a greater angle than red,but red is diffracted at a greater angle than blue.
E)both red and blue are refracted at the same angle and diffracted at the same angle.

Question

Quizplus · Accepted Answer

When white light passes through a glass prism, it undergoes refraction and gets split into its constituent colors due to the phenomenon of dispersion. The extent of refraction and dispersion depends on the wavelength of the light. Since Red light has the longest wavelength, it bends the least, and since blue light has the shortest wavelength, it bends the most when passing through the prism. Hence, red is refracted at a smaller angle than blue, and the answer choices A and B can be eliminated.

When white light is diffracted by a grating, interference patterns are formed, and each color is separated at specific angles, as the spacing between the gratings determines the angles at which constructive interference occurs. Again, since the separation between the gratings is inversely proportional to the wavelength of light, blue has to diffract more than red to satisfy the condition for constructive interference. Therefore, blue is diffracted at a greater angle than red. Hence, option C can be eliminated, leaving us with option D.

Therefore, the correct answer is D: blue is refracted at a greater angle than red, but red is diffracted at a greater angle than blue.

White Light Is in One Case Dispersed by Refraction on Passing